340 Systematic Paleontology 



Anoplia helderbergi-^ n. sp. 

 Plate LXI, Fig. 21 

 Description. — Shell smooth, moderately concavo-convex, semicircular 

 in outline and wider than long. Hinge-line equal to or greater than the 

 greatest width, of the shell. Cardinal areas linear. The cardinal margin 

 of the ventral valve bears three prominent laterally directed tubular 

 spines on each side of the umbo. Interior of dorsal valve with an abund- 

 ance of papillae arranged in radiating lines as in Chonetes. The ventral 

 valve has the two short muscular scars separated by the high, but very 

 short, bluntly terminating septum so characteristic of Anoplia. Surface 

 of both valves smooth ; the exceedingly delicate concentric lines of growth 

 hardly discernible. Specimens rarely exceed 6 mm. in widtli and 4.5 mm. 

 in length. 



Anoplia Jielderhergice differs from A. nudeaia, which it most resembles, 

 in being smaller, more transverse, less convex, but more particularly by 

 the smooth instead of lamellose exterior and the presence of tubular 

 spines; from the associated species of Chonetes, by the smooth exterior. 

 Occurrence. — Helderberg Formation, New Scotland Member. 

 21st Bridge. 



Collections. — Maryland Geological Survey, IT. S. National Museum. 



[Eowe.] 

 Anoplia nucleata (Hall) 

 Plate LXI, Figs. 22-2-1 



Leptirna nucleata Hall, 1857, Tenth Ann. Rept. N. Y. State Cab. Nat. Hist., 



p. 47. 

 Lepta-na nucleata Hall, 1859, Nat. Hist. N. Y., Pal., vol. iii, p. 419, pi. xciv, 



figs. la-Id. 1861. 

 Anoplia nucleata Hall and Clarke, 1892, ibidem, vol. viii, pt. i, p. 309, pi. xva, 



flgs. 17, 18; pi. XX, figs. 14-17. 

 Anoplia nucleata Weller, 1903, Geol. Surv. N. J., Pal., vol. iii, p. 325, pi. xli, 



fig. 9; p. 349, pi. xlvi, figs. 8-10. 



Description. — "Shell semicircular: ventral valve extremely gibbous, 

 abruptly depressed or flattened towards the lateral exti-emities ; beak (in- 

 ternal cast) very abruptly incurved, and divided by a central groove (left 

 by the mesial plate) which extends back nearly to the center of the valve : 



